feat: TUI帮助功能与样式改进

- 添加帮助信息栏 (bubbles help组件, Ctrl+H切换)
- 翻译卡片样式优化 (Padding空隙、上方内边距)
- 扩展build.sh支持跨平台编译
- release.yaml使用build.sh构建

internal/tui/keys.go

@@ -12,6 +12,7 @@ type KeyMap struct {
 	ScrollDown   key.Binding
 	ScrollTop    key.Binding
 	ScrollBottom key.Binding
+	Help         key.Binding
 }
 
 func NewKeyMap() KeyMap {
@@ -44,5 +45,21 @@ func NewKeyMap() KeyMap {
 			key.WithKeys("end"),
 			key.WithHelp("End", "底部"),
 		),
+		Help: key.NewBinding(
+			key.WithKeys("ctrl+h"),
+			key.WithHelp("Ctrl+H", "帮助"),
+		),
+	}
+}
+
+func (k KeyMap) ShortHelp() []key.Binding {
+	return []key.Binding{k.Help, k.Quit}
+}
+
+func (k KeyMap) FullHelp() [][]key.Binding {
+	return [][]key.Binding{
+		{k.Quit, k.Clear, k.SwitchLang},
+		{k.ScrollUp, k.ScrollDown, k.ScrollTop, k.ScrollBottom},
+		{k.Help},
 	}
 }

internal/tui/model.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"time"
 
+	"charm.land/bubbles/v2/help"
+	"charm.land/bubbles/v2/key"
 	"charm.land/bubbles/v2/spinner"
 	"charm.land/bubbles/v2/textarea"
 	"charm.land/bubbles/v2/viewport"
@@ -33,6 +35,7 @@ type model struct {
 	input    textarea.Model
 	viewport viewport.Model
 	spinner  spinner.Model
+	help     help.Model
 	keys     KeyMap
 
 	targetLang string
@@ -67,16 +70,22 @@ func NewApp(cfg *config.Config, t *translator.Translator) *tea.Program {
 	sp.Spinner = spinner.MiniDot
 	sp.Style = lipgloss.NewStyle().Foreground(lipgloss.Color("#8B5CF6"))
 
-	return tea.NewProgram(model{
+	hp := help.New()
+
+	m := model{
 		config:     cfg,
 		translator: t,
 		messages:   make([]ChatMessage, 0),
 		input:      ta,
 		viewport:   vp,
 		spinner:    sp,
+		help:       hp,
 		keys:       keys,
 		targetLang: getDefaultLang(cfg),
-	})
+	}
+
+	p := tea.NewProgram(m)
+	return p
 }
 
 func getDefaultLang(cfg *config.Config) string {
@@ -100,6 +109,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	case tea.WindowSizeMsg:
 		m.width = msg.Width
 		m.height = msg.Height
+		m.help.SetWidth(msg.Width)
 		m.updateLayout()
 
 	case translateMsg:
@@ -137,6 +147,9 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		case "end":
 			m.viewport.GotoBottom()
 		}
+		if key.Matches(msg, m.keys.Help) {
+			m.help.ShowAll = !m.help.ShowAll
+		}
 	}
 
 	m.input, cmd = m.input.Update(msg)
@@ -206,7 +219,12 @@ func (m *model) updateLayout() {
 
 	m.input.SetWidth(contentWidth)
 	m.viewport.SetWidth(contentWidth)
-	m.viewport.SetHeight(m.height - 12)
+
+	helpLines := 2
+	if m.help.ShowAll {
+		helpLines = 4
+	}
+	m.viewport.SetHeight(m.height - 12 - helpLines)
 	if m.viewport.Height() < 5 {
 		m.viewport.SetHeight(10)
 	}
@@ -217,6 +235,10 @@ func (m *model) updateLayout() {
 func (m *model) updateViewportContent() {
 	var b strings.Builder
 
+	if len(m.messages) > 0 {
+		b.WriteString("\n")
+	}
+
 	for _, msg := range m.messages {
 		b.WriteString(m.renderTranslationCard(msg))
 	}
@@ -252,7 +274,7 @@ func (m *model) renderTranslationCard(msg ChatMessage) string {
 			Render(msg.Error)
 		outputBlock = lipgloss.NewStyle().
 			Foreground(lipgloss.Color("#F87171")).
-			Padding(0, 3, 1, 3).
+			Padding(1, 3, 1, 3).
 			Width(m.viewport.Width()).
 			Render(outputContent)
 	} else {
@@ -260,7 +282,7 @@ func (m *model) renderTranslationCard(msg ChatMessage) string {
 			Width(m.viewport.Width() - 2).
 			Render(msg.Output)
 		outputBlock = lipgloss.NewStyle().
-			Padding(0, 3, 1, 3).
+			Padding(1, 3, 1, 3).
 			Width(m.viewport.Width()).
 			Render(outputContent)
 	}
@@ -299,9 +321,9 @@ func (m model) View() tea.View {
 	messages := m.viewport.View()
 	inputArea := m.renderInputArea()
 	infoBar := m.renderInfoBar()
-	spinnerView := m.renderSpinner()
+	helpView := m.help.View(m.keys)
 
-	content := header + "\n" + messages + inputArea + infoBar + spinnerView
+	content := header + "\n" + messages + inputArea + infoBar + helpView
 	v := tea.NewView(content)
 	v.AltScreen = true
 	return v